Description of the Giant Monopole Resonance in the Even-A $^{112-124}$Sn Isotopes within the Microscopic Model Including Quasiparticle-Phonon Coupling

TL;DR

This paper models the giant monopole resonance in tin isotopes using advanced microscopic approaches, incorporating quasiparticle-phonon coupling, and finds good agreement with recent experimental data, highlighting the importance of including quasiparticle interactions.

Contribution

It introduces a microscopic model including quasiparticle-phonon coupling for describing giant monopole resonances in tin isotopes, extending previous QRPA approaches.

Findings

The model accurately reproduces experimental resonance energies and widths.

Including quasiparticle-phonon coupling improves agreement with data.

The Skyrme T5 parametrization yields results consistent with measurements.

Abstract

We have calculated the strength distributions of the giant monopole resonance in the even-A tin isotopes (A = 112-124) which were recently measured in inelastic $\alpha$-scattering. The calculations were performed within two microscopic models: the quasiparticle random phase approximation (QRPA) and the quasiparticle time blocking approximation which is an extension of the QRPA including quasiparticle-phonon coupling. We used a self-consistent calculational scheme based on the HF+BCS approximation. The single-particle continuum was exactly included on the RPA level. The self-consistent mean field and the effective interaction were derived from the Skyrme energy functional. In the calculations, two Skyrme force parametrizations were used. The T5 parametrization with comparatively low value of the incompressibility of infinite nuclear matter ($K_{\infty}$ = 202 MeV) gives theoretical results in good agreement with the experimental data including the resonance widths.